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1.
C Paz-Ramos C A Cerdeiriña J Troncoso L Romaní 《Journal of Thermal Analysis and Calorimetry》2006,83(2):263-268
In the search of a useful
method for determining excess enthalpies as a function of temperature Calvet
calorimetry was employed. To this end, excess molar enthalpies
at 298.15 and 333.15 K and excess molar heat capacities
within 283.15–333.15 K were
determined for the 1-decanol+n-decane system
over the whole composition range. An isothermal flow Calvet-type calorimeter
was used for
measurements, whereas
were determined by means of a Setaram
Micro DSC calorimeter. Excess enthalpies within 283.15–333.15 K were
indirectly obtained through the integration of
(T) data using
at 298.15 K. The results obtained at 333.15 K agreed with those
determined directly, implying the thermodynamic consistency of the measured
data and, therefore, the reliability of the indirect method. 相似文献
2.
Z. L. Zhang M. H. Zhong J. Liu F. M. Liu Z. Z. Wang F. P. Zhong F. Wu 《Journal of Thermal Analysis and Calorimetry》1999,58(2):421-433
In this work some calorimetric measurements were also carried out on the electrorefining silver by using different current densities with a Calvet type microcalorimeter at room temperature. The ratio (R) of the measured heat (
m) to the input electric energy (
in) and the excess heat (
ex), i.e., difference between
m and
in during the electrorefining process, were discussed in terms of general thermodynamics. It was found that the R and
ex for silver were related with the current density or cell voltage employed in the experiment. The results obtained here also indicate that the heat generation under different conditions, such as different currents or voltages may be caused partially by the irreversibility of the process or by some unknown processes.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
3.
Enthalpic relaxation has been used to model the development of the glass transition in polymers, using kinetic parameters
determined separately. For this purpose the Kohlrausch-Williams-Watt stretched exponential function, relating the extent of
relaxation, Φ(t), to time t and an average relaxation time, τa, i.e.
where β is inversely related to the breadth of the relaxation spectrum, has been adopted. The relaxation time dependence
on temperature was taken to follow the modified Arrhenius relationship,
where T is the storage and T′ the fictive temperature, X is the structure factor and ΔH the activation enthalpy. Both have
been found to describe the process of enthalpic relaxation in polymer glasses and a direct comparison has been made with the
change in specific heat observed with different cooling rates in DSC experiments. The effect of variables, such as activation
enthalpies, pre-exponential factors, and the non-linear factors such as X and β on the observed Tgs and the temperature range over which the transition occurred have been determined.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
N. Binke L. Rong Y. Zhengquan W. Yuan Y. Pu Hu Rongzu Y. Qingsen 《Journal of Thermal Analysis and Calorimetry》1999,58(2):403-411
The kinetics of the first order autocatalytic decomposition reaction of highly nitrated nitrocellulose (HNNC, 14.14%N) was studied by using thermogravimetry (TG). The results show that the TG curve for the initial 50% of mass-loss of HNNC can be described by the first order autocatalytic equation
and that for the latter 50% mass-loss of HNNC described by the reaction equations
and
This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
5.
The example of the sequence of reactions
and the steady-state approximation are used to present a demonstration of the fact that the evolution of the reaction rates
under non-isothermal conditions depends on the ratio of the activation energies and on the heating rate. At the same time,
it is shown that, under isothermal conditions, the ratio of the activation energies plays no role.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
Minewaki K. Kato T. Yoshida H. Imai M. 《Journal of Thermal Analysis and Calorimetry》1999,57(3):753-758
We have investigated effects of shear flow on the structure of lamellar phase in hepta(oxyethylene glycol)—n—hexadecylether—water system using small-angle neutron scattering (SANS) under shear flow at the shear rates (
) from 10–3 s–1 to 50 s–1. In the range
=10–2 ~1 s–1, significant changes have been observed in both intensity and position of the reflection peak. Small-angle X-ray scattering without shear has been also measured at various concentrations and temperatures. It has been suggested from these results that the shear flow causes contraction of lamellar domains and formation of a new domain composed of disrupted bilayers which grows rapidly with increasing shear rate and reconstructs original microstructures.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
7.
A new approximation is proposed to the integral of the Boltzmann factor:
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相似文献
8.
Lajos Szirovicza 《Reaction Kinetics and Catalysis Letters》2009,96(2):311-317
The kinetics of the reactions of ClO3
− with HSO3
− and H2SO3 was studied by measuring the concentration of [Cl−] and [H+] both in chlorate-bisulfite and chlorate-sulfite/bisulfite solutions. A reaction mechanism was applied for simulation of
the experimental observations. Rate constants k1 = (1±0.5)·10−4 M−1 s−1 and k2 = (0.23±0.01) M−1 s−1 were determined for the following reactions:
9.
Emese Szabó Gábor L. Zügner István Szilágyi Sándor Dóbé Tibor Bérces Ferenc Márta 《Reaction Kinetics and Catalysis Letters》2008,95(2):365-371
The low-pressure discharge flow technique with resonance fluorescence monitoring of OH has been applied to study the kinetics
of the overall reaction:
10.
Ji-Ming Guo 《Journal of mathematical chemistry》2008,43(2):713-718
The energy E(G) of a graph G is defined as the sum of the absolute values of all the eigenvalues of the adjacency matrix of the graph G. This quantity is used in chemistry to approximate the total π-electron energy of molecules and in particular, in case G is bipartite, alternant hydrocarbons. In this paper, we show that if G = (V
1, V
2; E) is a bipartite graph with edges and , then
11.
The solubility of boric acid [B] in LiCl, NaCl, KCl, RbCl, and CsCl was determined as a function of ionic strength (0–6 mol ⋅ kg−1) at 25 ∘C. The results were examined using the Pitzer equation
12.
The thermal decomposition of zirconium oxyhydroxides prepared by the mixture of aqueous zirconium oxychloride solutions and aqueous solutions of sodium hydroxide or ammonium hydroxide under various conditions has been examined by thermogravimetry, differential thermal analysis, X-ray diffraction study and infrared spectrophotometry. As a result, it is seen that the thermal decomposition of zirconium oxyhydroxide, in which the composition is ZrO2-x(OH)2xyH2O where x2 and 1y<2, proceeds according to the following process:
13.
V. Balek M. Beneŝ J. Ŝubrt J. L. Pérez-Rodriguez P. E. Sánchez-Jiménez L. A. Pérez-Maqueda J. Pascual-Cosp 《Journal of Thermal Analysis and Calorimetry》2008,92(1):191-197
Emanation thermal analysis (ETA), thermogravimetry and high temperature XRD were used to characterize the thermal behavior
during dehydration of natural Na montmorillonite (Upton Wyoming, USA) and homoionic montmorillonite (MMT) samples saturated
with different cations, i.e. Li+, Cs+, NH4+, Mg2+ and Al3+. ETA results characterized radon mobility and microstructure changes that accompanied the mass loss of the samples due to
dehydration on heating in air. A collapse of interlayer space between the silicate sheets after water release from the MMT
samples was characterized by a decrease of the radon release rate, ΔE. Decreases in c-axis basal spacing (d
001) values determined from XRD patterns for the different montmorillonite samples follow the sequence:
14.
Teik-Cheng Lim 《Journal of mathematical chemistry》2008,43(1):304-313
The narcissus constant, N = 2.3983843828..., is defined as a number that fulfills the narcissistic infinite nested radical equation
15.
Yakov I. Tur’yan Fernando Mata Jorge Moyano Pavel Gorenbein Ron Kohen 《Journal of Solid State Electrochemistry》2007,11(1):10-20
The theory of the polarographic catalytic currents (mechanism CE) has been developed for the system: Ni2+-L-Xp− where L: pyridine (Py), nicotinamide (NA), N,N-diethylnicotinamide (DEN), nicotine (NC) and Xp−: NO−
3, AcO−, HPO2−
4 . The theory is based on the kinetic parallel heterogeneous catalytic reactions:
16.
Structural and thermal properties of the 20Li2O-80TeO2 glass were studied using X-ray diffraction analysis and differential scanning calorimetry techniques to understand and control
the crystallization process on this glass. The γ-TeO2, α-TeO2 and α-Li2Te2O5 phases were identified during the crystallization in this glass. Activation energies and Avrami exponent n were calculated
from non-isothermal measurements for glasses with different particle size. The mean values of Avrami exponent were obtained for glasses with 63–75 and 45–63 μm particle sizes such as , but glasses with particle size 38–45 μm and smaller than 38 g,m presented . 相似文献
17.
K. S. Gupta R. K. Mehta A. K. Sharma P. K. Mudgal S. P. Bansal 《Transition Metal Chemistry》2008,33(7):809-817
For getting an insight into the mechanism of atmospheric autoxidation of sulfur(IV), the kinetics of this autoxidation reaction
catalyzed by CoO, Co2O3 and Ni2O3 in buffered alkaline medium has been studied, and found to be defined by Eqs. I and II for catalysis by cobalt oxides and
Ni2O3, respectively.
18.
The kinetics of catalytic decomposition of NO over Cu/ZSM-5 catalyst has been studied in an integral flow reactor at atmospheric
pressure. Kinetic analysis is based on the assumption that the surface reaction represents the rate-determining step. On the
basis of theoretical considerations of different interactions between reactants and catalyst, and experimental evidences,
three different mechanistic kinetic models were chosen. Also a power-law model was tested. The best agreement has been achieved
with the model
19.
A u.v.–vis spectrophotometric study of the adduct formation of the nickel(II) Schiff base complexes,([NiL]) where L = [3-methoxysalophen,
N,N′-bis(3-methoxysalicylidene)-1,2-phenylenediimine] (1), [4-methoxysalophen, N,N′-bis(4-methoxysalicylidene)-1,2-phenylenediimine] (2), [5-methoxysalophen, N,N′-bis(5-methoxysalicylidene)-1,2-phenylenediimine] (3) and [Salophen, [N,N′-bis(salicylaldehydo)-1,2-phenylenediimine] (4) as donors with R2SnCl2 (R = methyl, phenyl and n-butyl) as acceptors have been investigated in chloroform, as solvent. Adducts have been characterized by 1H, 13C and 119Sn NMR, IR and electronic spectroscopy and CHN elemental microanalysis. The formation constants and the thermodynamic free
energies were measured using u.v.–vis spectrophotometry titration for 1:1 adduct formation at various temperatures (T = 278
to 308 K). The trend of the adduct formation of the nickel Schiff base complexes with a given tin acceptor decreases as follows:
20.
The solubility of siderite (FeCO3) at 25°C under constant CO2 partial pressure [p(CO2)] was determined in NaCl solutions as a function of ionic strength. The dissolution of FeCO3(s) for the reaction
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